Float glass is received when first heated to 650-700oC and then quickly cooled by blowing cold air onto either sides of glass. This glass is 4-6 times stronger than the ordinary one.
While the tensile strength of ordinary glass is 40 MPa (N/mm2), the thermally tempered glass may feature up to 120-200 MPa (N/mm2). The safety of thermally tempered glass depends on the glass thickness, edge work and on the fact if glass has holes or not.
Thermal tempering of glass also changes the glass break structure – when broken, such glass crumbles into small granular chunks instead of splintering into jagged shards. Thus we can get the safety glass by means of thermal tempering.
Glass thermal tempering also significantly increases its resistance against thermal tenses (temperature differences) while the allowable temperature gradient can reach 150-2000 C.
